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Ontogenetic development of storied ray pattern in cambium of Hippophae rhamnoides L.

100%

Myskow E., Zagorska-Marek B.

Acta Societatis Botanicorum Poloniae

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2004

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tom 73

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nr 2

Storied pattern, in the arrangement of both fusiform initials and the rays in cambium of Hippophae rhamnoides, develops in ontogeny relatively quickly and becomes clearly visible in terminal parenchyma of third and fourth annual ring. At first, anticlinal longitudinal divisions and restricted intrusive growth of fusiform initials lead to the formation of their characteristic horizontal tiers. Then, initiation of secondary rays, taking place rather within such tiers, not between them, makes possible the formation of storied ray pattern. New secondary rays originate most frequently from fusiform initials by their segmentation. This makes the appearance of ray tiers rather quick. However, the high order in the structure of cambium of Hippophae rhamnoides is also due to another, very curious and not known until now mechanism. It operates through limited in its range, thus highly controlled, vertical migration of rays on the cambial surface. This applies to asymmetrically positioned rays either primary, which are often originally sited "out of order" or secondary, initiated off-centre within the existing tiers. Excessively asymmetric rays, lying accidentally on the border between two neighbouring storeys, often undergo splitting and then the derivative rays move toward the centres of the storeys. Ray displacement is due to elimination of one or two of ray initial cells on one edge of the ray and simultaneous, multiple divisions adding new ray cells on the opposite edge.

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Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, South Carolina, USA

84%

Cicimurri D. J., Knight J. L.

Acta Palaeontologica Polonica

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2009

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tom 54

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nr 4

A diverse vertebrate fauna, dominated by elasmobranch taxa, was collected from the upper Oligocene (Chattian) Chandler Bridge Formation in Summerville, Dorchester County, South Carolina. Nearly 3,500 teeth and dermal denticles are assigned to 29 species of sharks and rays, and our sample includes the oldest known occurrence of the whale shark, Rhincodon, as well as a new skate, Raja mccollumi sp. nov. The Chandler Bridge elasmobranch assemblage is comparable in species diversity to Chattian assemblages of Virginia and North Carolina, USA, and Germany. Notable absences from Germany include Rhincodon, Hemipristis, and Sphyrna zygaena, likely reflecting the influence of colder water on the North Sea Basin during the Chattian. Squaloids, pristiophoroids, and hexanchoids are known from Chattian deposits of the Albemarle Embayment (North Carolina), Salisbury Embayment (Virginia), and North Sea Basin, but these taxa are absent from the Chandler Bridge assemblage, perhaps because of shallow, warm water (20 to 25°C) conditions within the more southerly Charleston Embayment.

3

Two thousand parasites on a single ray: An infection with two species of skin monogeneans on a blotched fantail ray kept in an aquarium

84%

Justine J. L., Grugeaud A., Keller F., Leblanc P.

Acta Parasitologica

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2010

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tom 55

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nr 3

286-290

A blotched fantail ray, Taeniurops meyeni (Müller et Henle, 1841), was captured in New Caledonia, South Pacific, and kept in a tank for quarantine before exhibition at the Nouméa public aquarium. After 24 days, the ray exhibited a heavy infection with two species of skin monogeneans. A freshwater bath allowed the collection of 1,914 monogeneans, including 1,453 capsalids, Neoentobdella taiwanensis Whittington et Kearn, 2009, on the ventral surface, and 461 monocotylids, Dendromonocotyle pipinna Chisholm et Whittington, 2004, on the dorsal surface. More than 300 monogeneans were prepared on slides to allow precise measurements. Capsalids and monocotylids occupied about 6% and 0.2% of the total ventral and dorsal ray surfaces, respectively.

4

The effect of gamma irradiation dose on cucumber [Cucumis sativus L.] haploid embryo production

84%

Faris N. M., Nikolova V., Niemirowicz-Szczytt K.

Acta Physiologiae Plantarum

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1999

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tom 21

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nr 4

Ograniczanie wyników

1 Acta Palaeontologica Polonica

1 Acta Parasitologica

1 Acta Physiologiae Plantarum

1 Acta Societatis Botanicorum Poloniae

1 Cicimurri D. J.

1 Faris N. M.

1 Grugeaud A.

1 Justine J. L.

1 Keller F.

1 Knight J. L.

1 Leblanc P.

1 Myskow E.

1 Niemirowicz-Szczytt K.

1 Nikolova V.

1 Zagorska-Marek B.

1 2010

1 2009

1 2004

1 1999

Ontogenetic development of storied ray pattern in cambium of Hippophae rhamnoides L.

Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, South Carolina, USA

Two thousand parasites on a single ray: An infection with two species of skin monogeneans on a blotched fantail ray kept in an aquarium

The effect of gamma irradiation dose on cucumber [Cucumis sativus L.] haploid embryo production